By David Goldman, CNN Business

The stock market is on the comeback trail.

After another wobbly session, the Dow soared 287 points, or 1.2%, on Friday. It was the index's best day since August.

The Dow had soared 400 points at the open before giving up most of those gains and then resuming its rally. The Dow lost 1,378 points over Wednesday and Thursday.

The broader S&P 500 jumped 1.4% on Friday. The Nasdaq, which has taken the brunt of the recent stock market turbulence, spiked 2.3%.

Despite Friday's rebound, all three major indexes suffered their worst weeks since March. And the S&P 500 is down three straight weeks. That hasn't happened since the Brexit referendum of June 2016.

Investing experts weren't exactly sure what turned stocks negative by midday. The driving forces behind this week's downturn -- trade war and interest rate fears -- were around before this week, and yet market volatility is spiking.

"The sellers have control right now," said Justin Walters, co-founder of Bespoke Investment Group. "The scariest sell offs are the ones you can't tie to a specific reason."

Stocks had turned sharply south over the past week because investors are concerned about rising interest rates. As the Federal Reserve raises rates to keep the economy from overheating, investors have been getting out of bonds, driving down their price and driving up their yields. Suddenly, the return on bonds has become competitive with some stocks — particularly risky tech stocks.

Rising interest rates also increase borrowing costs for households and businesses, eating into corporate profits.

"What we are seeing now is changing sands. The ground isn't stable and people are figuring out where to go next," said JJ Kinahan, chief market strategist with TD Ameritrade.

Tech stocks have come under fire because they are some of the riskiest and most expensive parts of the market. Investors fear that tech companies may not hold up well in a downturn, particularly as interest rates spike. A proxy for the tech sector had its sharpest plunge in seven years on Wednesday.

But Big Tech on Friday regained some of its losses. Facebook (FB), Apple (AAPL), Amazon (AMZN), Netflix (NFLX) and Google (GOOGL) were all up.

Asian and European markets also came back Friday. The Hang Seng soared 2.2%. Stocks in Shanghai rose 0.9% and the Nikkei rose 0.5%. Stocks in London, Germany and France all rose about a half percentage point.

Markets had bounced back Friday morning following news that President Donald Trump plans to meet next month with Chinese leader Xi Jinping at the G-20 summit. That eased some of investors' fears about another trade war escalation. China also reported reported its exports rose nearly 15% in September, stronger than expected. That suggests China is weathering the first waves of new tariffs that the Trump administration imposed on $50 billion of Chinese exports this summer.

But Kinahan is still worried about US-China trade talks. He thinks that a deal is key in order for the markets to get back on track, adding that a full-blown trade war could undo much of the positives from the Trump administration's pro-business policies.

"The concern is that if nobody blinks, it could negate all the tax cuts we had," he said.

Earnings season also kicked off Friday morning, with JPMorgan (JPM) and Citigroup (C) reporting their quarterly finances before the bell. Wall Street analysts expected the financial sector to post another incredibly profitable quarter — and JPMorgan managed to beat their already lofty expectations.

In times of market turbulence, there's nothing like soaring profits to calm investors' nerves.

Rebounds after disastrous market selloffs are common. Investors who think the market may be oversold look to buy stocks they think are suddenly cheap.

But markets are fickle.